1. Field of the Invention
The present invention relates to a pull-type clutch pressure plate actuating mechanism, and more particularly, it relates to a pressure plate actuating mechanism wherein a plurality of intermediary levers are utilized between the clutch pressure plate and diaphragm spring to gain mechanical advantage in disengaging the clutch.
2. Description of the Related Art
A pressure plate actuating assembly in an automobile clutch generally includes a bowl-shaped clutch cover fixed to the flywheel of an engine, a pressure plate disposed within the clutch cover, and a diaphragm spring for impelling the pressure plate toward the flywheel. In one example of a pull-type a clutch, a pressure plate actuating assembly includes a retaining collar holding the diaphragm spring and coupled to a release mechanism. The retaining collar in this construction is impelled toward the flywheel by the diaphragm spring. Furthermore, a lever element is provided supported by the retaining collar in between the diaphragm spring and the pressure plate.
In the pressure plate actuating assembly having the retaining collar and the lever element, impelling force from the diaphragm spring is transmitted to the pressure plate via the intervening lever element while the clutch is engaged. Therein, the impelling force on the pressure plate is multiplied according to a lever ratio of the lever element. Consequently, pressing force greater than the impelling force of the diaphragm spring is applied to the pressure plate.
Accordingly, an actuating assembly employing a diaphragm spring having a low spring rate in conjunction with the lever element nonetheless can transmit sufficient magnitude of pressing force to the pressure plate, due to the mechanical advantage gained by the lever element. A diaphragm spring having a lower spring rate reduces force of resistance to disengagement of the pressure plate during a clutch release operation. In particular, a reduced load to be overcome in releasing the clutch reduces the leg power needed to work the clutch operating pedal in a vehicular installation.
In pressure plate actuating assemblies as above, however, spacial limitations have restricted the lever ratio of the lever element. Consequently, while it would be advantageous to reduce the clutch-releasing load of the pressure plate actuating assembly still further, the mechanical advantage that can be gained by means of the lever element alone in the conventional pressure plate actuating assembly is insufficient for this purpose.